n, n΄-3, 4-di(methylamino)-1, 2, 5-oxadiazole (1f) was prepared by dehydration of n, n΄-3, 4-di(methylamino)glyoxime (2f) in aqueous potassium hydroxid at 170-180 ˚c. under similar conditions n, n΄-3, 4-di(benzylamino)-1, 2, 5-oxadiazole (1c) and n, n΄-3, 4-di(isopropylamino)-1, 2, 5-oxadiazole (1e) were not obtained, but, n, n΄-3, 4-di(ethylamino)-1, 2, 5-oxadiazole (1g) was appeared with smal...

background: the use of the ionizing radiation in the medical practice has evolved since its beginnings. their benefit for the patient is considerable in term of comfort, diagnostic and therapeutic effectiveness. it is estimated that 30% to 50% of critical decisions in medical approaches is based on x-ray examination. using the x-ray as a diagnostic means by clinicians requires appropriate and a...

the dual diene/1,3-dipolar character of 1-h-imidazole 3-oxide, hio 1, allows this compound toparticipate in a competitive diels-alder (da)/1,3-dipolar cycloaddition (13dc) reaction toward c=sdouble bond of the electro-deficient sulfonyl methane sfm 2. the b3lyp/6-311++g(d,p) calculatedrelative gibbs free energies indicate that among the studied 13dc and da reactions, former iscompletely preferr...

The impact of interplanetary shocks on the magnetosphere can trigger magnetic substorms that intensify auroral electrojet currents. These currents enhance ground field perturbations (d$B$/d$t$), which in turn generate geomagnetically induced (GICs) be detrimental to power transmission infrastructure. We perform a comparative study d$B$/d$t$ variations response two similarly strong shocks, but w...

this work presents a numerical study to investigate the heat transfer characteristics of a 2-d rectangular composite porous radiant burner (cprb). in the construction of porous burner, the porous layer is considered to be of composite type consisting of upstream and downstream layers with equal thickness but with different physical and radiative properties. in the present work, a two dimensiona...

sulfonic acid functionalized sba-15 (sba-pr-so3h) as a new nanoporous acid catalyst was used in the one-pot synthesis of polyhydroquinolines derivatives via the hantzsch four component condensation reaction of aldehydes, b-ketoesters, dimedone and ammonium acetate under solvent free conditions with short reaction time in excellent yields. sba-pr-so3h was proved to be an efficient heterogeneous ...

1, 8-dioxo-octahydroxanthene derivatives have efficiently been synthesized from dimedone and aromatic aldehydes using [fe(iii)(salen)cl] complex as an efficient and homogeneous catalyst in molten tetrabutyl ammonium bromide. this methodology offers several advantages, such as good yields, short reaction times, simple procedure, and mild conditions.

-The acidic properties of acid-modified montmorillonite and vermiculite were determined by pyridine and ammonia adsorption to correlate with the alkylating and dehydrating activity of the activated samples. Treatment of the minerals with different concentrations of hydrochloric acid results in the variation of overall acidity and density of acidic sites. Infrared (IR) spectral and differential ...

background: although the precise etiology of multiple sclerosis (ms) is unknown, it seems that both genetic and environmental factors are important. recent studies suggest that low serum vitamin d levels are important environmental factor in ms. the aim of this study was to compare the serum levels of vitamin d between ms patients and healthy subjects, and to determine its association with disa...